OpenZFS 8264 - want support for promoting datasets in libzfs_core

Authored by: Andrew Stormont <[email protected]>
Reviewed by: Andriy Gapon <[email protected]>
Reviewed by: Matthew Ahrens <[email protected]>
Reviewed by: Dan McDonald <[email protected]>
Approved by: Dan McDonald <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Ported-by: Giuseppe Di Natale <[email protected]>

OpenZFS-issue: https://www.illumos.org/issues/8264
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/a4b8c9a
Closes #6254 

2 files changed, 31 insertions, 14 deletions

diff --git a/lib/libzfs/libzfs_dataset.c b/lib/libzfs/libzfs_dataset.c
index f1346b69c..bc630919a 100644
--- a/lib/libzfs/libzfs_dataset.c
+++ b/lib/libzfs/libzfs_dataset.c
@@ -29,6 +29,7 @@
  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  * Copyright 2016 Nexenta Systems, Inc.
  * Copyright 2016 Igor Kozhukhov <[email protected]>
+ * Copyright 2017 RackTop Systems.
  */
 
 #include <ctype.h>
@@ -3731,8 +3732,7 @@ int
 zfs_promote(zfs_handle_t *zhp)
 {
 	libzfs_handle_t *hdl = zhp->zfs_hdl;
-	zfs_cmd_t zc = {"\0"};
-	char parent[MAXPATHLEN];
+	char snapname[ZFS_MAX_DATASET_NAME_LEN];
 	int ret;
 	char errbuf[1024];
 
@@ -3745,31 +3745,25 @@ zfs_promote(zfs_handle_t *zhp)
 		return (zfs_error(hdl, EZFS_BADTYPE, errbuf));
 	}
 
-	(void) strlcpy(parent, zhp->zfs_dmustats.dds_origin, sizeof (parent));
-	if (parent[0] == '\0') {
+	if (zhp->zfs_dmustats.dds_origin[0] == '\0') {
 		zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
 		    "not a cloned filesystem"));
 		return (zfs_error(hdl, EZFS_BADTYPE, errbuf));
 	}
 
-	(void) strlcpy(zc.zc_value, zhp->zfs_dmustats.dds_origin,
-	    sizeof (zc.zc_value));
-	(void) strlcpy(zc.zc_name, zhp->zfs_name, sizeof (zc.zc_name));
-	ret = zfs_ioctl(hdl, ZFS_IOC_PROMOTE, &zc);
+	ret = lzc_promote(zhp->zfs_name, snapname, sizeof (snapname));
 
 	if (ret != 0) {
-		int save_errno = errno;
-
-		switch (save_errno) {
+		switch (ret) {
 		case EEXIST:
 			/* There is a conflicting snapshot name. */
 			zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
 			    "conflicting snapshot '%s' from parent '%s'"),
-			    zc.zc_string, parent);
+			    snapname, zhp->zfs_dmustats.dds_origin);
 			return (zfs_error(hdl, EZFS_EXISTS, errbuf));
 
 		default:
-			return (zfs_standard_error(hdl, save_errno, errbuf));
+			return (zfs_standard_error(hdl, ret, errbuf));
 		}
 	}
 	return (ret);
diff --git a/lib/libzfs_core/libzfs_core.c b/lib/libzfs_core/libzfs_core.c
index 8e36d8459..8142f2c63 100644
--- a/lib/libzfs_core/libzfs_core.c
+++ b/lib/libzfs_core/libzfs_core.c
@@ -23,6 +23,7 @@
  * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  * Copyright (c) 2017 Datto Inc.
+ * Copyright 2017 RackTop Systems.
  */
 
 /*
@@ -206,6 +207,28 @@ lzc_clone(const char *fsname, const char *origin,
 	return (error);
 }
 
+int
+lzc_promote(const char *fsname, char *snapnamebuf, int snapnamelen)
+{
+	/*
+	 * The promote ioctl is still legacy, so we need to construct our
+	 * own zfs_cmd_t rather than using lzc_ioctl().
+	 */
+	zfs_cmd_t zc = { "\0" };
+
+	ASSERT3S(g_refcount, >, 0);
+	VERIFY3S(g_fd, !=, -1);
+
+	(void) strlcpy(zc.zc_name, fsname, sizeof (zc.zc_name));
+	if (ioctl(g_fd, ZFS_IOC_PROMOTE, &zc) != 0) {
+		int error = errno;
+		if (error == EEXIST && snapnamebuf != NULL)
+			(void) strlcpy(snapnamebuf, zc.zc_string, snapnamelen);
+		return (error);
+	}
+	return (0);
+}
+
 /*
  * Creates snapshots.
  *
@@ -333,7 +356,7 @@ lzc_exists(const char *dataset)
 {
 	/*
 	 * The objset_stats ioctl is still legacy, so we need to construct our
-	 * own zfs_cmd_t rather than using zfsc_ioctl().
+	 * own zfs_cmd_t rather than using lzc_ioctl().
 	 */
 	zfs_cmd_t zc = {"\0"};